A substantial proportion of synthetic fabrics now in use are copolymers of ethylene glycol and terephthalic acid, sold under trade names which include DACRON, FORTREL, KODEL and BLUE C POLYESTER. The removal of oily soil and oily stains from the surface of such fabrics is well recognized to be technically difficult to achieve using laundry compositions of the type most generally accessible to consumers.
Substances which have been suggested for use in consumer products as soil release agents include polymers which contain ethylene terephthalate segments randomly interspersed with polyethylene glycol segments. See, for example, U.S. Pat. No. 3,962,152, Nicol et al, issued June 8, 1976. A soil release polyester of this type, commercially known as MILEASE T, is further disclosed in U.S. Pat. No. 4,116,885, Derstadt et al, issued Sept. 7, 1978. Other commercial variants are sold as PERMALOSE, ZELCON and ALKARIL products (see, for example, Canadian Patent No. 1,100,262, Becker et al, issued May 5, 1981; U.S. Pat. No. 4,238,531, Rudy et al, issued Dec. 9, 1980; and British Patent Application No. 2,172,608, Crossin, published Sept. 24, 1986). Commercial suppliers of soil release polyesters include ICI, duPont and Alkaril (formerly Quaker Chemical Co.).
Soil release compositions used in industrial textile treatment applications are well-known. Application of such compositions is under controlled conditions and is free from the formulation constraints encountered in the detergent arts. Padding and heat curing, in the absence of high levels of detergent chemicals, are illustrative of the processes used. Polyesters have successfully been used for industrial soil release treatments of polyester surfaces, but recent trends are toward rather expensive fluorochemical treatments.
The development of economical, product-stable and formulation-compatible soil release agents for consumer product compositions is not straightforward. In contrast with the simple and controlled environments in which industrial textile treatment agents are generally used, soil release agents in consumer laundry products will usually be exposed to various detersive ingredients, such as anionic surfactants, alkaline builders and the like. Such chemicals may reduce the effectiveness of soil release agents, for example, by preventing their deposition on fabrics. The soil release agents may, reciprocally, reduce the laundry benefits of detersive ingredients, for example, by interfering with the action of surfactants, optical brighteners, antistatic agents or softeners, all of which are commonly present in modern detergent compositions. In a "thru-the-wash" mode, it is especially important that no formulation ingredient, including the soil release agent, should promote the redeposition of suspended soils in the laundry liquor; this would dull the appearance of the laundered fabrics.
Arguably, the most difficult of consumer laundry products, for the purpose of incorporating soil release agents, are granular detergent compositions. Compatibility requirements of soil release agents, especially with the alkaline, anionic detergent environments commonly present in such detergent compositions, provide a substantial technical challenge.
The end-capped esters of the present invention have been developed to meet these needs.
It is an object of the present invention to provide novel compositions which can be used as effective and product compatible soil release agents in consumer products having widely varying formulas, such as granular detergent compositions and fabric conditioner sheets.
It is a further object of the invention to provide novel ester oligomers and low molecular weight polyesters.
These and other objects are secured herein, as will be seen from the following disclosure.